A smoking article, a filter and a method of manufacturing a smoking article

ABSTRACT

A smoking article includes a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section, and a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section. A resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section, and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied.

TECHNICAL FIELD

Embodiments of the invention relate to a smoking article, a filter and a method of manufacturing a smoking article.

BACKGROUND

The resistance to draw of a smoking article is a measure of the pressure required to force smoke through the smoking article at a certain specified rate. A smoking article can be configured by the manufacturing process to have a resistance to draw within a pre-defined range. The resistance to draw through a smoking article generally drops with increased ventilation.

SUMMARY

Embodiments of the invention provide, in a first aspect, a smoking article comprising a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section and a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section, wherein a resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section, and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied.

The first filter section can have a first tow weight of fibrous filtration material, and the second filter section can have a second tow weight of fibrous filtration material and the second tow weight of fibrous filtration material is lower than the first tow weight of fibrous material.

The pressure drop per unit length of the first filter section can be more than 5 mmH₂O/mm, and the pressure drop per unit length of the second filter section can be less than 5 mmH₂O/mm. The resistance to gaseous flow through the second filter section can be more than 15 times lower than the resistance to gaseous flow through the first filter section.

The first filter section can be formed from a first homogenous filtration material, and the second filter section can be formed from a second homogenous filtration material.

The second filter section can be separate from the first filter section, and/or moveable relative to the first filter section to control the ventilation into the first filter section.

The smoking article can further comprise a sleeve configured to move relative to the first filter section, wherein the second filter section is fixed within the sleeve, and the level of ventilation is varied by altering a position of the sleeve relative to the first filter section.

The sleeve can be rotatable with respect to the first filter section, and the level of ventilation can be varied by altering an angular position of the sleeve relative to the first filter section.

The first filter section can have a length of 5 to 25 mm, the second filter section can have a length of 5 to 25 mm, and/or the ventilation arrangement can provide ventilating air at 6 mm to 35 mm from a mouth end of the smoking article.

The first and second filter sections can comprise tow filaments, and the first filter section can differ from the second filter section by one or more of: tow weight, number of tow filaments in unit volume, cross-section of tow filaments and degree of crimping.

The second filter section can comprise at least one air passage extending longitudinally through the length thereof.

The air passage can have a diameter of between 1 and 7 mm.

The second filter section can comprise fibrous filtration material formed having an annular cross section.

The second filter section can comprise a tube of fibrous filtration material and the air passage can extend along a central longitudinal axis through the length of the second filter section.

Embodiments of the invention provide, in a second aspect, a method of manufacturing a smoking article, the method comprising forming a first filter section with a first resistance to gaseous flow through its length, forming a separate second filter section with a second resistance to gaseous flow through its length, wherein the second resistance to gaseous flow is lower than the first resistance to gaseous flow, and assembling the first filter section and second filter section with one or more additional components to form the smoking article, wherein the smoking article is configured to allow the ingress of a selectively variable amount of air.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal cross-sectional view of a part of a smoking article according to a first embodiment of the invention;

FIG. 2 is a perspective view of the smoking article illustrated in FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of a part of a smoking article according to a second embodiment of the invention;

FIG. 4 is a perspective view of the smoking article illustrated in FIG. 3;

FIG. 5 is a graph showing the relationship between level of ventilation and open cigarette pressure drop (PD) for an example conventional smoking article and a smoking article according to the invention;

FIG. 6a is a plan view of a blank forming a wrapper for a smoking article according to a third embodiment of the invention;

FIG. 6b is a plan view of a rod article to which the blank of FIG. 6a is applied to form the smoking article according to the third embodiment of the invention;

FIG. 7a is a plan view of a blank for forming a wrapper for a smoking article according to a fourth embodiment;

FIG. 7b is a longitudinal cross-sectional view of the smoking article according to the fourth embodiment; and

FIG. 8 is a schematic flow diagram showing a method of manufacturing a smoking article.

DETAILED DESCRIPTION

FIG. 1 illustrates a smoking article 10 according to a first embodiment. The smoking article 10 is a cigarette in the present example. However, other smoking articles can be used, and the term smoking article is used to also refer to cigars or cigarillos, whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products (i.e. products in which flavour is generated from a smoking material by the application of heat without causing combustion of the material) and aerosol generating products such as e-cigarettes. For convenience, these will be referred to as “smoking articles” in this specification.

Smoking articles such as cigarettes and their formats are often named according to the cigarette length: “regular” (typically in the range 68-75 mm, e.g. from about 68 mm to about 72 mm), “short” or “mini” (68 mm or less), “king-size” (typically in the range 75-91 mm, e.g. from about 79 mm to about 88 mm), “long” or “super-king” (typically in the range 91-105 mm, e.g. from about 94 mm to about 101 mm) and “ultra-long” (typically in the range from about no mm to about 121 mm).

They are also named according to the cigarette circumference: “regular” (about 23-25 mm), “wide” (greater than 25 mm), “slim” (about 22-23 mm), “demi-slim” (about 19-22 mm), “super-slim” (about 16-19 mm), and “micro-slim” (less than about 16 mm). Accordingly, a cigarette in a king-size, super-slim format will, for example, have a length of about 83 mm and a circumference of about 17 mm. Cigarettes in the regular, king-size format are preferred by many customers, namely with a circumference of from 23 to 25 mm and an overall length of from 75 to 91 mm.

Each format may be produced with filters of different lengths, smaller filters being generally used in formats of smaller lengths and circumferences. Typically the filter length will be from 15 mm, associated with short, regular formats, to 30 mm, associated with ultra-long super-slim formats. The tipping paper will have a greater length than the filter, for example from 3 to 10 mm longer.

Smoking articles and filters described hereinafter can be manufactured in any of the above formats. The smoking article can, for instance, be from 70 to 100 mm in length and from 14 to 25 mm in circumference.

The terms ‘upstream’ and ‘downstream’ used herein are relative terms defined in relation to the direction of mainstream smoke (or other aerosol) drawn though a smoking article in use.

The smoking article 10 of the example of FIG. 1 comprises a source of smokable material, such as tobacco, attached to a filter arrangement which comprises a first filter section 12 and a second filter section 14. The source of smokable material is in the form of a tobacco rod 11, which is attached to the first filter section 12. The second filter section 14 is located downstream of the first filter section 12 and tobacco rod 11. A ventilation arrangement 17 provides a user controllable variable level of ventilation into the first filter section 12, as described in more detail below.

The resistance to gaseous flow through the length of the second filter section is lower than the resistance to gaseous flow through the length of the first filter section; and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied. The reduced resistance of the second filter section 14 results in the first filter section 12 having a greater influence on the overall resistance to gaseous flow of the filter arrangement. As ventilation is increased into the second filter section 14, a lower resistance path is created for flow through the filter arrangement, therefore significantly reducing the resistance to draw experienced by the consumer, when compared to lower levels of ventilation. The reduced resistance of the second filter section 14 when compared to the first filter section therefore enhances the change in the resistance to draw experience by the consumer as the ventilation is altered, providing the consumer with a greater sensory indication that the ventilation has been changed.

The smoking article 10 comprises a first part comprising the tobacco rod 11 and the first filter section 12. The tobacco rod 11 and first filter section 12 are connected with a covering layer to affix the first filter section to the tobacco rod, which is formed of tipping paper. The tobacco rod 11 and first filter section 12 are referred to as a tobacco unit. The elongate tobacco rod 11 and first filter section 12 define a longitudinal axis of the smoking article.

A second part of the smoking article comprises the second filter section 14 and a sleeve 13 which is movable relative to the first part of the smoking article. The sleeve is in the form of a tube extending around the circumference of the tobacco rod 11 and/or first filter section 12. The tube can be cylindrical. The sleeve 13 is formed of paper. The second filter section 14 is securely attached and fixed within the sleeve. The first and second filter sections 12,14 each comprise filtration material which is wrapped in a sheet material, which may be paper, e.g. plugwrap. The first and second filter sections form a filter arrangement. The first filter section 12 is upstream of the second filter section 14. The second filter section 14 is at a mouth end of the sleeve 13, adjacent to, and separate from, the first filter section 12. Alternatively, the first and second filter sections are connected.

The tobacco rod 11 and attached first filter section 12 are described as connected by tipping paper (not shown). The tipping paper is a standard tipping paper, or a relatively thick recessed tipping paper, or a board type tipping paper.

The smoking article 10 is provided with the ventilation arrangement 17 configured to allow adjustment of a ventilation of the smoking article 10. The ventilation arrangement 17 comprises one or more second ventilation area 15 on the sleeve 13, upstream of the second filter section 14. The smoking article further comprises one or more first ventilation area 16 around the first filter section 12. For example, the one or more first ventilation area 16 is defined by a layer(s) of sheet material around the first filter section or around the filtration material of the first filter section. The ventilation arrangement 17 provides for ventilating air to enter into the first filter section. The terms “upstream” and “downstream” are relative to the direction of the passage of smoke along the longitudinal axis of the smoking article 10, i.e. “downstream” indicates in a direction toward the mouth end of the smoking article 10.

Ventilation areas 15,16 are formed as ventilation apertures or air permeable material. In some embodiments, when ventilation areas 15 on the sleeve 13 are exposed, air can flow into the body of the smoking article 10. When second ventilation areas 15 on the sleeve 13 and the corresponding first ventilation areas 16 around the first filter section 12 are aligned, air can flow into the body of the smoking article 10. Ventilation areas 15,16 are aligned by rotation of the first part of the smoking article relative to the second part. In particular, the ventilation is controlled by rotation of the sleeve 13 relative to the first filter section 12. The ventilation arrangement 17 provides a selectable variable level of ventilation controlled by adjusting the overlap of the second ventilation area 15 with the first ventilation area 16. The amount of ventilation depends on the effective ventilating area, which is determined by the area of the overlap of the first and second ventilation areas. The level of ventilation can be selected by selecting a position of the second part relative to the first part e.g. by rotation of the second part relative to the first part. Thus, the ventilation arrangement 17 provides for a variable size of effective ventilation area, providing a variable intake of air, substantially upstream of the second filter section.

The first filter section 12 and second filter section 14 are made of a known filtration material. The filtration material for both filter sections can be tow, for example, cellulose acetate tow. The filtration material of the first filter section is homogenous, and independently, the filtration material of the second filter section is homogenous. The term “homogenous” is used to mean that the filtration material is substantially uniform throughout each filter section, and in particular, is uniform in a longitudinal and/or radial direction through each of the first and second filter sections 12,14. At least one physical property of the homogenous first filter section is different to the homogenous second filter section.

The first filter section 12 provides a first resistance to gaseous flow through the length thereof. The resistance to gaseous flow through the length of the first filter section is determined by the filtration material of the first filter section. The resistance to gaseous flow indicates the pressure required to draw smoke through the length of the first filter section 12 at a particular rate. The term “pressure drop” can be used in place of “resistance to gaseous flow”. Pressure drop can be given in units of distance height of water (mmH₂O). The first filter section has a first pressure drop per unit length, or resistance to gaseous flow per unit length, which is constant in a longitudinal direction through the first filter section 12. Pressure drop per unit length is given per millimetre, i.e. in units of mmH₂O/mm. The first pressure drop per unit length is determined by the filtration material of the first filter section.

The second filter section 14 provides a second resistance to gaseous flow through the length thereof. The resistance to gaseous flow through the length of the second filter section is determined by the filtration material of the second filter section 14. The resistance to gaseous flow through the length of the second filter section 14 defines a second pressure drop. The second pressure drop or resistance to gaseous flow indicates the pressure required to draw smoke through the length of the second filter section 14 at a particular rate. The second resistance to gaseous flow (or pressure drop) per unit length is substantially constant in a longitudinal direction through the second filter section 14. The second filter section 14 can be considered as comprising a filtration material having a second pressure drop per unit length.

In aspects of the present invention, the resistance to gaseous flow through the length of the first filter section 12 is greater than the resistance to gaseous flow through the length of the second filter section 14. In another aspect, the tow weight of the second filter section 14 is lower than the tow weight of the first filter section 12. The second density provided by the second filter section 14 is lower than the first density provided by the first filter section 12. Optionally, the first pressure drop across the first filter section 12 is greater than the second pressure drop across the second filter section 14.

The one or more ventilation areas 15,16 allowing selectable ventilation are upstream of the second filter section 14. The relatively low resistance to draw through the length of the filter arrangement downstream of the ventilation area 15 provides an increased variation in an overall resistance to draw from the mouth end of the smoking article 10, as ventilation is varied.

The ventilation arrangement 17 is located substantially upstream of the second filter section 14. Ventilation of a smoking article 10 reduces the resistance to draw from the mouth end of the smoking article 10. The ingress of ventilating air reduces the volume of air drawn through the length of smoking article 10 upstream of the ventilation areas, reducing the volume of air which experiences the resistance to gaseous flow upstream of the ventilating areas. The ventilating air enters directly with substantially no resistance, so the overall resistance to draw is reduced. In particular, the ingress of air through the ventilation areas 15 reduces the effect of the resistance to gaseous flow through the section of the smoking article 10 upstream of the ventilation areas 15. The effect of the resistance to gaseous flow through the smoking article 10 downstream of the ventilation areas 15 is unchanged by variations in ventilation.

The relatively low resistance to gaseous flow provided by the lower density of the second filter section 14 (relative to the first filter section 12) downstream of the ventilation areas 15 defines a minority of the resistance to gaseous flow through the full length of the filter arrangement. Alternatively, the second filter section 14 provides a relatively small contribution to the overall resistance to draw from the mouth end of the smoking article 10. The contribution of the one or more sections upstream of the ventilation area 15 on the overall resistance to draw is greater by comparison. The ingress of air reduces the effect of the pressure drop or resistance to gaseous flow through the upstream section only, and the downstream section with a lower resistance to gaseous flow or pressure drop is unaffected by the ventilation. Therefore, a relatively large proportion of the overall resistance to draw from the mouth end of the smoking article 10 is affected by the change in ventilation of the smoking article 10. The decreased density of the second filter section 14 downstream of the ventilation areas 15 increases the proportion of the resistance to draw which is affected by the change in ventilation of the smoking article 10. The decreased density of the second filter section 15 provides an increase in the effect of an increased ventilation on the overall resistance to draw from the mouth end of the smoking article 10.

As the level of ventilation is varied, the resistance to draw from the mouth end of the smoking article 10 also changes. As the amount of ventilating air entering the smoking article 10 increases, the overall resistance to draw decreases. The relatively low pressure drop or resistance to gaseous flow through the second filter section 14 (e.g. achieved with a relatively low density of filter material) provides a relatively large change in overall resistance to draw caused by an increased level of ventilation. Therefore, as the level of ventilation is varied over a range selectable by the user, the resistance to draw from the mouth end of the smoking article 10 varies over a relatively large range as a result of the lower density of the second filter section 14. Thus, the variation in resistance to draw from the mouth end of the smoking article is accentuated as the ventilation is varied. This can give the user a greater sensory indication that the ventilation level has been varied.

In some examples of the invention, the second filter section has a pressure drop per unit length of less than 5 mmH₂O/mm. Alternatively, the second filter section has a pressure drop per unit length of less than a value selected from: 4 mmH₂O/mm, 3 mmH₂O/mm, 2 mmH₂O/mm, 1.5 mmH₂O/mm, and 1 mmH₂O/mm.

In some examples of the invention, the first filter section has a pressure drop per unit length of more than 5 mmH₂O/mm. Alternatively, the first filter section has a pressure drop per unit length of more than a value selected from: 6 mmH₂O/mm, 7 mmH₂O/mm, 8 mmH₂O/mm, 9 mmH₂O/mm, 10 mmH₂O/mm, 11 mmH₂O/mm, and 12 mmH₂O/mm.

In some aspects, the pressure drop per unit length of the second filter section is between 1 and 5 mmH₂O/mm, and the pressure drop per unit length of the first filter section is between 5 and 15 mmH₂O/mm. In some examples, the pressure drop per unit length of the second filter section is less than 5 mmH₂O/mm, and the pressure drop per unit length of the first filter section is more than 5 mmH₂O/mm. The upstream filter section has a pressure drop per unit length which is higher than a pressure drop per unit length of the downstream filter section. The upstream filter section has a pressure drop per unit length which is higher than any of the example values specified, and a pressure drop per unit length of the downstream filter section is lower than any of the example values specified.

In some examples, the resistance to gaseous flow through the length of the second filter section is lower than the first filter section by at least a multiple value selected from one of: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15.

For example, the resistance to gaseous flow through the length of the second filter section is between 2 and 15 times lower than through the length of the first filter section. Optionally, the second pressure drop per unit length of the second filter section is between 5 and 12 times lower than the first pressure drop per unit length of the first filter section.

In some aspects, the ventilation arrangement 17 is located at a downstream end of the first filter section 12. In some examples, the ventilation arrangement is located less than 10 mm from the downstream end of the first filter section 12.

The pressure drop per unit length of the first and second filter sections is determined (at least partially) by the physical structure of the filtration material forming the filter sections. The first and second filter sections can both comprise fibrous material, comprising tow filaments. For a filtration material comprising tow filaments, the pressure drop per unit length can be determined by the amount or number of tow filaments in a particular volume or length. The tow weight is a measure of the amount of tow fibres in a certain volume. The pressure drop per unit length can also be determined by the cross-section of the tow filaments. For example, the tow filaments can have an X-shaped cross-section or a Y-shaped cross-section. The cross-sectional area can also affect the pressure drop per unit length. The tow weight can provides an indication of the density of a fibrous material within the filter section. The pressure drop per unit length can also be determined by the amount or degree of crimping (i.e. folding) of the filaments, during the manufacturing processes. These factors affecting the pressure drop per unit length of the filter sections are known, and can be selected to obtain the required pressure drop per unit length for each of the first and second filter sections individually. Thus, the first and second filter sections comprise filtration material which has a physical property determined by a different selection of any one or more of the above characteristics. The first and second filter sections are manufactured using filtration material formed or treated to have the required properties, for example as above, providing the different pressure drop per unit length for the first and second filter sections.

FIG. 2 is a perspective view of the part of the smoking article 10 illustrated in FIG. 1. As illustrated in FIG. 2, the tobacco rod 11 and first filter section 12 are dimensioned to rotate as a unit around a longitudinal axis within the sleeve 13. A restraining means (not shown) retains the first part and second part in a fixed longitudinal arrangement, and prevents extension of the smoking article 10. Thus, the first part cannot slide longitudinally relative to the second part, i.e. the sleeve is not movable longitudinally relative to the tobacco unit.

The level of ventilation can be selected by selecting an angular position of the sleeve 13 relative to the first filter section 12.

In some examples, the ventilation areas 15 are configured to increase in size non-linearly with respect to angular position. The ventilation areas 15 are configured such that the level of ventilation has a substantially linear dependence on the angular position of the sleeve 13 relative to the first filter section 12.

In some aspects, the one or more ventilation areas 15 maintain a fixed longitudinal position relative to the first and second filter sections, when the sleeve 13 is rotated relative to the first filter section 12.

In the present embodiment, the second filter section 14 is securely attached and fixed within the sleeve 13. Rotation of the second filter section 14 causes a corresponding rotation of the sleeve 13 relative the first filter section 12.

By selecting a different angular position of the second filter section 14 relative to the first filter section 12, the registry between the ventilation areas 15 in the sleeve 13 and the ventilation areas 16 in the sheet material or plugwrap around the first filter section 12 can be selectively increased or decreased. The level of ventilation in the smoking article 10 can therefore be increased or decreased.

FIG. 3 is a longitudinal cross-sectional view of a part of a smoking article according to a second embodiment of the invention. The overall layout is similar to the example of FIGS. 1 and 2 described above, the same parts having the same reference numerals, and parts other than those described remaining unchanged.

In the embodiment of FIG. 3, the second filter section 24 is formed to have an air passage 28 passing longitudinally through its centre. The second filter section 24 and air passage 28 form a tubular filter section extending along the longitudinal axis of the smoking article 20. The second filter section 24 is formed from fibrous filtration material having an annular cross-section. Alternatively, the air passage 28 may pass longitudinally along a non-central path through the second filter section. Optionally, the second filter section may be formed to have a plurality of air passages which pass longitudinally therethrough.

The air passage 28 reduces the resistance to gaseous flow through the length of the second filter section 24. The resistance to gaseous flow through the length of the second filter section 24 is lower than the resistance to gaseous flow through the length of the first filter section 12.

The dimensions of the second filter section 24 will depend on various factors such as the desired resistance to draw or the second filter section 24 relative to the first filter section 12, the properties of the filter tow and the level of plasticiser, such as triacetin, added to the filter tow. However, in examples herein, the outer circumference of the second filter section is between 15 and 25 mm, for instance between 22 mm and 25 mm, or 23.95 mm. The internal diameter of the air passage 28 is preferably between 1 mm and 7 mm, for instance between 3 mm and 6 mm, or 4.8 mm.

FIG. 4 is a perspective view of the smoking article illustrated in FIG. 3. As illustrated in FIG. 4, the air passage 28 is located to pass longitudinally through the centre of the second filter section 24. Alternatively, the air passage 28 may pass longitudinally along a non-central path through the second filter section 24. Optionally, the second filter section 24 may be formed to have a plurality of air passages which pass longitudinally therethrough.

EXAMPLE

Table 1 below illustrates calculated values for the resistance to draw from the mouth end of a conventional “Smoking Article 1” compared with calculated values for the resistance to draw from the mouth end of an example “Smoking Article 2”, according to an example of the invention. Each smoking article has a filter with total length 27 mm, and variable ventilation system allowing ingress of air at a distance 16.5 mm from the mouth end of the filter. The filter is formed of the first and second filter sections which are axially aligned. The mouth end filter section (second filter section) is 8 mm long, and the tobacco end filter section (first filter section) is 19 mm long. Both smoking articles have an identical tobacco rod with a resistance to draw (pressure drop) of 43.43 mm H₂O.

The conventional filter of Smoking Article 1 has a provides a substantially uniform pressure drop per unit length of approximately 5 mmH₂O/mm, for both first and second filter sections. The pressure drop is 85 mmH₂O for the first filter section with a length of 19 mm, and a pressure drop of 40 mmH₂O for the second filter section with a length of 8 mm.

In the example of Smoking Article 2, according to the invention, the second filter section is an 8 mm filter section at the mouth end of the filter, which has a pressure drop of 8 mmH₂O. This provides a relatively low pressure drop per unit length of 1 mmH₂O/mm. The upstream first filter section has a length of 19 mm adjacent the tobacco rod, and has a relatively high pressure drop per unit length. This provides a pressure drop per unit length of 7.11 mmH₂O/mm.

TABLE 1 Smoking Article 1 Smoking Article (example conventional 2 (example smoking article) of invention) Pressure Pressure drop (mmH₂O) drop (mmH₂O) First filter section (19 mm) 85 135 PD Second filter section (8 mm) 40 8 PD PD of filter downstream of 78.03 68.39 vent PD of filter upstream of vent 46.97 74.61 PD Tobacco Rod 43.43 43.43 Total PD at 40% ventilation 132.27 139.22 Total PD at 60% ventilation 114.19 114.61 Total PD at 80% ventilation 96.11 92.00

The pressure drop through the full smoking article (including tobacco rod) is determined for ventilation values with a level of ventilation between 40% and 80% ventilated. For the conventional Smoking Article 1 the pressure drop varies from 132.27 to 96.11 mmH₂O ventilation as ventilation increases. However, in the Smoking Article 2, according to the invention, the pressure drop varies from 139.22 mmH₂O to 92 mmH₂O over the same ventilation range. Thus, the drop of 47.22 mm H₂O provided by the invention, compared with only 36.16 mm H₂O for the conventional smoking article, provides an increase change in pressure drop (i.e. more varied resistance to draw from the mouth end) when varying the ventilation of the smoking article. These results are illustrated in FIG. 5, in which the y-axis indicates pressure drop and the x-axis indicated the percentage ventilation.

In some embodiments, the pressure drop downstream of the ventilation arrangement 17 is decreased further by reducing the distance between the mouth end of the smoking article and the one or more ventilation areas.

In some examples of the invention, the ventilation areas allow the ingress of air at a distance from the mouth end which is less than 15 mm. Alternatively, the distance from the mouth end of the ventilation are is less than a value selected from: 14 mm, 13 mm, 12 mm, 11 mm, and 10 mm.

FIG. 6a is a plan view of a blank 30 forming a wrapper for a smoking article according to a third embodiment of the invention. FIG. 6b is a plan view of a rod article 32 to which the blank 30 of FIG. 6a is applied to form the smoking article. The smoking article comprising the blank 30 has substantially the same functions as described above. Features have the same arrangement and function unless otherwise described.

The blank 30 is configured to wrap twice only around the whole circumference of the rod article 32. The blank 30 is configured to define two complete layers extending around the circumference of the rod article 32, and comprises areas to define an inner layer and an outer layer.

The blank 30 comprises a control element 34 movable in a channel 36, configured to control ventilation and limit movement.

The control element 34 is movable circumferentially within a limited range. The control element 34 is movable between a first engaging surface and a second engaging surface. The first engaging surface and second engaging surface define a circumferentially extending channel 36 in which the control element 34 is movable.

The control element 34 defines first and second limiting surfaces 34 a, 34 b at the edges of the control element in the direction of movement, i.e. at the circumferential edge of the control element 34. Contact of the first and second limiting surfaces 34 a, 34 b of the control element 34 between the first engaging surface and the second engaging surface limits relative rotation between the first and second parts of the smoking article.

The first and second limiting surfaces 34 a, 34 b extend at an angle to a longitudinal axis of the smoking article. The first and second engaging surfaces also extend at an angle to the longitudinal axis of the smoking article, and/or at an angle to the axis of movement of the control element. The first and second engaging surfaces extend at the same angle and/or have a complementary shape to the first and second limiting surfaces 34 a, 34 b.

The blank 30 comprises the first and second spacing sections 38 a, 38 b. The first and second spacing sections 38 a, 38 b are configured to directly attach to and circumscribe the rod articles. The first and second spacing sections 38 a, 38 b have the function of spacing a plurality of optional indexing surfaces at a correct radial distance to allow indexing. The first and second spacing sections 38 a, 38 b are longitudinally spaced apart.

The control element 34 is configured to directly overlie one of the spacing sections 38 a, 38 b. The control element is movable over the spacing section 38 a, the spacing section providing a substantially smooth exterior surface over which the control element is easily moved.

Referring to FIG. 6b , the rod article 32 includes a tobacco rod 11, similar to those previously described, and first and second filter sections 40, 42 downstream of the tobacco rod 11. The second filter section 42 is provided, as a tubular section substantially similar to the second filter section 24 described in relation to the second embodiment, downstream of the first filter section 41 and tobacco rod 11, at the mouth end of the smoking article. The first filter section 40 is provided between the second filter section 42 and the tobacco rod 11. When the blank 30 is wrapped around the rod article 32, the control element 34 is spaced by the spacing section from the first filter section 40. The first filter section 40 optionally defines a first indexing surface 40 a, and so does not provide a smooth surface for the control element.

The first and second spacing sections 38 a, 38 b are optionally connected by a spacer connection 44. The first and second spacing sections 38 a, 38 b extend circumferentially over the two layers of the first blank 30. The spacer connection 44 is adjacent a leading edge of the first blank 30, i.e. the point on the blank 30 first wrapped around the rod article 32.

The spacer connection 44 and longitudinally adjacent areas of the spacing sections 38 a, 38 b are initially affixed to the rod article to begin wrapping of the first blank 30, for example, with adhesive. The spacer connection 44 provides for the blank 30 to have a single initial area of attachment to the rod article 32. The spacing sections 38 a, 38 b are not affixed as independent elongate sections of sheet material, requiring separate attachment to the rod article 32. Thus, the connection of the leading edges of the spacing sections 38 a, 38 b improves initial attachment of the blank 30 to the rod articles.

The spacer connection 44 has a trailing edge 44 a at a circumferentially opposite end of the spacer connection 44 to the leading edge. The spacer connection trailing edge 44 a extends between the first and second spacing sections 38 a, 38 b. The spacer connection trailing edge 44 a extends at an angle to a longitudinal axis of the smoking article.

The control element 34 is formed on a support section 46 of the blank 1401. The control element 34 defines the longitudinally extreme area of the section to which the control element is attached. Thus, the first and second limiting surfaces 34 a, 34 b of the control element 34 extend longitudinally beyond the section to which the control element is attached. The support section 44 is attached to the first and second spacing sections with frangible connections. The frangible connections are circumferentially extending line of perforations. The support section 46 extends one time around the whole circumference of the smoking article, e.g. to form a tube. The control element is curved as a part of that tube.

The support section 46, optionally supports a second indexing surface 48. In particular, the second indexing surface optionally comprises a pawl 48 formed on a pawl support unit 50, which is attached to the support section 46. The pawl 48 is configured to extend between the first and second spacing sections 38 a, 38 b, and engage with the optional first indexing surface 40 a.

The support section 46 comprises a support section leading edge 46 a. The support section leading edge 46 a defines the initial point of the support section 46 which is first wrapped around the rod article 32. The support section leading edge 46 a extends at an angle to a longitudinal axis of the smoking article.

30 A trailing edge 46 b of the support section 46 extends substantially parallel to the longitudinal axis of the smoking article.

The spacer connection trailing edge 44 a, support section leading edge 46 a and first and second spacing sections 38 a, 38 b define an aperture 52 in the blank 30. The aperture 52 provides a space in which the support section 46 is movable.

In some examples, the aperture 52 has a circumferential extent which is greater than a circumferential extent of movement of the control element 34. Thus, the spacer connection trailing edge 44 a does not determine the range of movement of the control element 34.

The area of blank 30 forming the inner layer, e.g. on the first spacing section 38 a, comprises a ventilation area 54. In some examples, the ventilation area 54 comprises a single aperture. Alternatively, the ventilation area 54 comprises a plurality of discrete permeable areas or apertures. For example, the apertures are formed by electroperforation (EP).

The control element 34 has a further function in controlling the ventilation of the smoking article. In particular, the control element 34 directly controls the ventilation of the smoking article by selectively covering one or more ventilation areas. The control element 34 is configured to be movable over one or more ventilation areas in a radially adjacent, and integrally formed, part of the smoking article. The control element 34 is formed of a material which is substantially impermeable to air, in particular, paper which is not permeable to air. The control element 34 is configured to cover the one or more ventilation areas of the smoking article, such that ventilation air cannot enter the smoking article through an area which is covered by the control element 34. The control element is impermeable to air between the first and second limiting surfaces 34 a, 34 b. The first and second limiting surfaces 34 a, 34 b define both the limits of rotation and define the amount of ventilation area which is covered or uncovered.

Thus, the control element 34 has the dual function of both directly controlling a level of ventilation by covering a part of a ventilation area and limiting relative movement of the first and second parts of the smoking article between maximum and minimum levels of ventilation.

In some aspects, the smoking article comprises a further ventilation area 56. For example, the first filter section 40 comprises the further ventilation area 56. The ventilation area 54 is arranged to at least partially coincide with the further ventilation area 56. The further ventilation area 56 comprises a plurality of discrete ventilation areas or apertures, for example, in a circumferentially extending line. The further ventilation area 56 can be formed by a laser. Generally, one or more of the ventilation areas 54, 56 comprise a plurality of discrete ventilation areas or apertures.

FIG. 7a is a plan view of a blank 60 forming a wrapper for a smoking article according to a fourth embodiment. FIG. 7b is longitudinal cross-sectional view of a smoking article 62 to which the blank 60 of FIG. 7a has been applied. The smoking article 62 comprising the blank 60 has substantially the same functions as described above. Features have the same arrangement and function unless otherwise described.

Referring to FIG. 7 b, the rod article 62 includes a tobacco rod 11, similar to that previously described, and first and second filter sections 12, 14 downstream of the tobacco rod 11. The second filter section 14 is provided downstream of the first filter section 12 and tobacco rod 11, at the mouth end of the smoking article. The first filter section 12 is provided between the second filter section 14 and the tobacco rod 11. The first filter section 12 is divided into a first part 12′ and a second part 12″ by a cut 12′″, allowing the first part 12′ of the first filter section 12 to move relative to the second part 12″.

The blank 60 is configured to wrap twice, and in the present example twice only, around the whole circumference of the rod article 62. The blank 60 has a first section 60 a which first wraps around the rod article 62 forming an inner layer and a second section 60 b which then wraps around the first section 60 a, forming an outer layer. The blank 60 is therefore configured to define two complete layers extending around the circumference of the rod article 62, and comprises areas 60 a, 60 b to define an inner layer and an outer layer.

The first section 60 a of the blank 60 comprises a first end portion 60 a′ connected to the second filter section 14 and to the first part 12′ of the first filter section 12, and therefore connecting the second filter section 14 and the first part 12′ of the first filter section 12 together. The first section 60 a of the blank 60 also comprises a second end portion 60 a″ connected to the second part 12″ of the first filter section 12. The second section 60 b of the blank 60 is separated into a first part 60 b′ and a second part 60 b″ by a cut 61.

The blank 60 comprises, on the first section 60 a, a control element 64 movable in a circumferentially extending channel 66, configured to control ventilation and limit movement.

The control element 64 is movable circumferentially within a limited range. The control element 64 is movable between a first engaging surface and a second engaging surface. The first engaging surface and second engaging surface define the circumferentially extending channel 66 in which the control element 64 is movable.

The control element 64 defines first and second limiting surfaces 64 a, 64 b at the edges of the control element in the direction of movement, i.e. at the circumferential edge of the control element 64. Contact of the first and second limiting surfaces 64 a, 64 b of the control element 64 with the first engaging surface and the second engaging surface of the circumferentially extending channel 66 limits relative rotation between the first and second parts of the smoking article.

The first and second limiting surfaces 64 a, 64 b extend at an angle to a longitudinal axis of the smoking article. The first and second engaging surfaces also extend at an angle to the longitudinal axis of the smoking article, and/or at an angle to the axis of movement of the control element. The first and second engaging surfaces extend at the same angle and/or have a complementary shape to the first and second limiting surfaces 64 a, 64 b.

A longitudinal movement restricting arrangement 65 comprises a sliding element 67 which is arranged to move between first and second restricting elements 68 a and 68 b. Sliding element 67 is attached to first and second restricting elements 68 a and 68 b with a frangible connection. The frangible connection is a circumferentially extending line of perforations. The part of the blank including the sliding element 67, control element 64, first and second restricting elements 68 a and 68 b and circumferentially extending channel 66 extends one time around the whole circumference of the smoking article, e.g. to form a tube. The sliding element 67 is attached to first part 60 b′ of the second section 60 b of the blank 60, together with the first part 60 a′ of the first section 60 a of the blank, and therefore moves, together with the first part 60 a′ of the first section 60 a, the second filter section 14 and the first part 12′ of the first filter section 12, relative to 30 the second part 60 a″ of the first section 60 a of the blank 60 and the second part 12″ of the first filter section 12.

The second section 60 b of the blank 60 forming the outer layer, comprises a ventilation area 69′ at a location 69 on the blank. In some examples, the ventilation area 69′ comprises a single aperture. Alternatively, the ventilation area 69′ comprises a plurality of discrete permeable areas or apertures. For example, the apertures are formed by electroperforation (EP). The ventilation area 69′ is arranged to align with the channel 66 when the blank 60 is wrapped around the rod article 62.

The control element 64 has a further function in controlling the ventilation of the smoking article. In particular, the control element 64 directly controls the ventilation of the smoking article by selectively blocking one or more ventilation areas. The control element 64 is configured to be movable relative to one or more ventilation areas in a radially adjacent, and integrally formed, part of the smoking article. The control element 64 is formed of a material which is substantially impermeable to air, in particular, paper which is not permeable to air. The control element 64 is configured to move between the ventilation area 69′ and the underlying rod article 62 of the smoking article, such that ventilation air cannot enter the smoking article through the channel 66 which is blocked by the control element 64. The control element is impermeable to air between the first and second limiting surfaces 64 a, 64 b. The first and second limiting surfaces 64 a, 64 b define both the limits of rotation and define the amount of ventilation area which is covered or uncovered.

Thus, the control element 64 has the dual function of both directly controlling a level of ventilation by covering a part of a ventilation area and limiting relative movement of the first and second parts of the smoking article between maximum and minimum levels of ventilation.

In some embodiments, the first filter section 12 comprises flavourant in the form of botanical particles. However, the first filter section 12 can comprise other forms of flavourant, such as one or more capsules, a thread loaded with flavourant, flavourant dispersed in filter tow, flavour impregnated particles or a sheet material comprising a flavourant, which lie upstream of the ventilation area 69′. The level of ventilation in the smoking article 10 controls the dilution of smoke which passes through the first part of the smoking article 10 with air which enters the smoking article 10 through the ventilation area 69′. Therefore the level of ventilation also controls the dilution of flavoured smoke which has passed through the flavourant with unflavoured air which enters the smoking article through the ventilation area 69′. The level of flavour in the smoking article can therefore be increased or decreased.

In some aspects, the blank 60 comprises a further ventilation area (not shown) at a location 63 on the blank downstream of the variable ventilation arrangement 69′. The further ventilation area comprises a plurality of discrete ventilation areas or apertures, for example, in a circumferentially extending line. The further ventilation area can be formed by a laser. Generally, one or more of the ventilation areas comprise a plurality of discrete ventilation areas or apertures. The further ventilation area provides a constant minimum level of ventilation which is unaffected by the variable amount of ventilation from the ventilation area 69′. The amount of ventilation provided by the further ventilation area can be predetermined in the manufacture of the smoking article 10 and is, for instance, between 5% to 50% of the volume of smoke and/or other aerosol generated by said smoking article passing through the filter section when said variable ventilation is at its minimum level. The variable ventilation arrangement 69′, 66 can be arranged to provide ventilation which is user controllable within a sub-range within the range of from 0% to 90% of the volume of smoke and/or other aerosol generated by said smoking article passing through the filter section, for instance from 0% to 50% ventilation.

FIG. 8 illustrates schematically a method 100 of manufacturing smoking articles according to the invention. The method 100 comprises forming a first filter section with a first resistance to gaseous flow or pressure drop (step 110). The first filter section is formed from a known filtration material, for example, cellulose acetate tow. A second filter section is separately produced (step 120). The second filter section is also formed from cellulose acetate tow. The resistance to gaseous flow through the length of the second filter section is lower than the resistance to draw through the length of the first filter section. Optionally, the pressure drop of the second filter section is lower than the pressure drop of the first filter section.

The different pressure drop properties of the first and second filter sections are determined during manufacturing of the first and second filter sections. In some aspects, the fibrous filtration material, i.e. tow elements are configured differently for the first and second filter sections. For example, the second filter section is formed with a different diameter tow, compressed more than the first filter section, different cross-section, to obtain the different properties (i.e. lower density). The pressure drop properties of the first and second filter sections are not substantially changed or modified during use of the smoking article.

In an embodiment, the second filter section is formed with an annular cross section, to obtain a lower density. The first and second filter sections is formed from the same fibrous filtration material, and formed to have different cross sections in order to obtain the different properties. In some examples, the filter arrangement is formed of a single piece including the first filter section and the second filter section.

The first filter section and second filter section are assembled with one or more additional components to form the filter arrangement of the smoking article (step 130). The first and second filter sections may be longitudinally aligned with a source of smokeable material. Any other known filter components can be added to the smoking article. Examples of further filter components include a third filter section, for instance a filter section with particulate material (e.g. carbon, activated charcoal) or an additional hollow section. The first and/or second filter sections can each be considered as comprising one or more discrete filter sections. The filter sections can be considered as generally upstream and downstream of the variable ventilation area. The one or more upstream filter section has a higher resistance to gaseous flow than the one or more downstream filter section.

Wrapping material is applied to the smoking article assembly to attach the component parts. The paper wrapping material is tipping paper. In addition, a sleeve is wrapped around the smoking article. The sleeve is configured to move relative to the first filter section and, optionally, is securely attached to the second filter section.

The smoking article is configured to allow the ingress of a selectively variable amount of air upstream of the second filter section. For example, ventilation apertures are formed in the outermost layer of paper wrap and/or the paper sleeve. The ventilation apertures are formed by a mechanical cutting tool or a laser. The ventilation apertures are formed in the wrapping material prior to the assembly of the smoking article (i.e. pre-perforated apertures) or, optionally, when the smoking article is assembled.

The ventilation has been described by entering the smoking article upstream of the second filter section, and in particular, into the first filter section. Alternatively, the ventilation can be at least partially into the second filter section, e.g. adjacent an upstream end of the second filter section. A ventilating position for ingress of air which includes both upstream of the second filter section and optionally an upstream part (e.g. upstream quarter) of the second filter section is termed as located substantially upstream of the second filter section.

The properties of the filter sections can be defined in terms of any of: pressure drop per unit length, resistance to gaseous flow per unit length, pressure drop, resistance to gaseous flow, tow weight, or density. The filter sections can be defined in terms of the filtration material having a resistance to gaseous flow, which can be considered as independent of the length of the filter section.

The smoking article can comprise one or more ventilation areas providing a base level of ventilation. Such ventilation areas (not shown) are not variable in size.

In order to address various issues and advance the art, the entirety of this disclosure illustrates by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for a superior smoking article. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future. 

1. A smoking article comprising: a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section; and a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section, wherein the smoking article comprises a first part and a second part and the level of ventilation can be selected by selecting a position of the second part relative to the first part; wherein a resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section; and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied.
 2. The smoking article as claimed in claim 1, wherein the first filter section has a first tow weight of fibrous filtration material, and the second filter section has a second tow weight of fibrous filtration material; and the second tow weight of fibrous filtration material is lower than the first tow weight of fibrous material.
 3. The smoking article as claimed in claim 1, wherein the pressure drop per unit length of the first filter section is more than 5 mmH2O/mm, and the pressure drop per unit length of the second filter section is less than 5 mmH2O/mm.
 4. The smoking article as claimed in claim 1, wherein the resistance to gaseous flow through the second filter section is lower than the resistance to gaseous flow through the first filter section by at least a multiple value selected from one of: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and
 15. 5. The smoking article as claimed in claim 1, wherein the first filter section is formed from a first homogenous filtration material, and the second filter section is formed from a second homogenous filtration material.
 6. The smoking article as claimed in claim 1, wherein the second filter section is separate from the first filter section, and/or moveable relative to the first filter section to control the ventilation into the first filter section.
 7. The smoking article as claimed in claim 1, wherein the second part further comprises a sleeve configured to move relative to the first filter section, wherein the second filter section is fixed within the sleeve, and the level of ventilation is varied by altering a position of the sleeve relative to the first filter section.
 8. The smoking article as claimed in claim 7, wherein the sleeve is rotatable with respect to the first filter section, and the level of ventilation is varied by altering an angular position of the sleeve relative to the first filter section.
 9. The smoking article as claimed in claim 1, wherein the first filter section has a length of 5 to 25 mm, the second filter section has a length of 5 to 25 mm, and/or the ventilation arrangement provides ventilating air at 6 to 35 mm from a mouth end of the smoking article.
 10. The smoking article as claimed in claim 1, wherein the first and second filter sections comprise tow filaments, and the first filter section differs from the second filter section by one or more of: tow weight, number of tow filaments in unit volume, cross-section of tow filaments and degree of crimping.
 11. The smoking article as claimed in claim 1, wherein the second filter section comprises at least one air passage extending longitudinally through the length thereof.
 12. The smoking article as claimed in claim 11, wherein the air passage has a diameter of between 1 and 7 mm.
 13. The smoking article as claimed in claim 1, wherein the second filter section comprises fibrous filtration material formed having an annular cross section.
 14. The smoking article as claimed in claim 1, wherein the second filter section comprises a tube of fibrous filtration material and the air passage extends along a central longitudinal axis through the length of the second filter section.
 15. A filter for a smoking article comprising: a filter arrangement comprising a first filter section and a second filter section, the second filter section being located downstream of the first filter section; and a ventilation arrangement configured to provide a user controllable level of ventilation into the first filter section, wherein the filter comprises a first part and a second part and the level of ventilation can be selected by selecting a position of the second part relative to the first part; wherein a resistance to gaseous flow through the length of the second filter section is lower than a resistance to gaseous flow through the length of the first filter section; and the resistance to gaseous flow through the length of the filter arrangement remains substantially constant as the level of ventilation is varied.
 16. A method of manufacturing a smoking article, the method comprising: forming a first filter section with a first resistance to gaseous flow through its length; forming a separate second filter section with a second resistance to gaseous flow through its length, wherein the second resistance to gaseous flow is lower than the first resistance to gaseous flow; and assembling the first filter section and second filter section with one or more additional components to form the smoking article such that the second filter section is located downstream of the first filter section in the smoking article, wherein the smoking article is configured to allow the ingress of a selectively variable amount of air. 